Add new constructors to YamlNode subclasses.

These constructors make it easy to use the same code for extracting data from
both YAML and non-YAML objects.

R=rnystrom@google.com

Review URL: https://codereview.chromium.org//343063002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/yaml@37665 260f80e4-7a28-3924-810f-c04153c831b5
8 files changed
tree: 03c8200eb3e4bf80a6528b05f9af4ea2fccae054
  1. pkgs/